1. Field of the Invention
The present invention relates generally to cushion or seat structures for automobiles, aircraft, office or home furniture, and similar items wherein a plastic foam is employed to integrate a pliable fabric-like cover and a reinforcing grid or skeleton; also to methods of making such structures.
2. Description of the Prior Art
A method has been described in applicant's prior U.S. Pat. No. 4,046,611 granted Sept. 9, 1977 for making cushions of plastic foam with integrated fabric cover, wherein the method involves a preliminary operation of preshaping the cover sheet in such manner as to take advantage of its capabilities for peripheral shrinkage in order to avoid formation of wrinkles in the preshaped blank resulting from the preshaping operation. Such preshaping is done preliminary to vacuum molding of the cover sheet into its final configuration, and to its integration with plastic foam introduced into the mold while the cover sheet is held by vacuum in conformity with the mold surface.
It has also been disclosed in applicant's prior U.S. application Ser. No. 557,247, filed Mar. 11, 1975 to vacuum form a fabric or sheet plastic cover as part of an integrated cushion structure, by the use of a perforated or air pervious elastic diaphragm, supported across the mold cavity, over which the cover sheet is placed preliminary to vacuum forming. The surface of the diaphragm is made non-sliding relative to the cover sheet, with the result that the final drawing or tensioning of the cover sheets in the forming and molding process, as well therefore as the thickness of the sheets, are kept substantially uniform over the entire surface of the final cushion structure.
And finally, in applicant's prior French application No. 74/06942, filed Feb. 28, 1974, there is described a method for making cushions or seats of plastic foam, wherein different areas of an integrated cover can be formed of different fabrics or films. The method there disclosed in particular employs means for locking the various portions of the cover fabric in position on a mold, using a profile strip which projects marginally from the cover assembly. After molding, the projecting portion of the profile strip may be cut or torn away leaving a finishing bead of good appearance hiding the junction of the cover parts.
All of the methods described above lead to the embodiment of cushions with integrated covers, whose cover fabrics or sheets were stretched over plastic foam formed in situ within the cover to provide the cushion body or matrix, wherein the entire surface of the cover was uniformly tensioned or stretched and the thickness of the cover fabric was uniform, throughout the entire surface of the cushion, thus eliminating weak spots constituting points at which wear might start.
Nevertheless those prior cushion structures could not be mounted on their supports except by conventional means and this required relatively lengthy mounting times and high cost, especially because of the skilled craftwork involved. Nor were such prior cushion structures able to insure the uniformity of shape for finished seats which would be demanded in fully automated manufacture.